Meteorological catalysts of dust events and particle source dynamics of affected soils during the 1930s Dust Bowl drought, Southern High Plains, USA

Abstract

Abstract Mineral dust aerosols are a key component of the Earth system and a growing public health concern under climate change, as levels of dustiness increase. The Great Plains in the USA is particularly vulnerable to dust episodes, but land-atmosphere interactions contributing to large-scale dust transport are poorly constrained. This study compiled one of the longest quantitative, spatially-comprehensive records of dust events in the core Dust Bowl region never before available. Combined with experiment station reports from the Soil Conservation Service, reanalysis data products, and contemporary field surveys using a Portable In-Situ Wind Erosion Laboratory (PI-SWERL), the study examined meteorological catalysts for dust events and surficial dynamics of particle emission on the Southern High Plains (SHP). Multivariate statistical analyses of dust event variance yield 6 principal components capturing ˜60% of the variance of all dust event days. Results identified four dominant modes of dust events related to the season of occurrence and principal meteorological controls. A broader assessment of the potential emissivity of SHP soils reveals that disturbed surfaces begin to emit dust at a magnitude-higher rate than undisturbed surfaces as soon as the wind velocity reaches the threshold, increasing linearly with windspeed. Conversely, crusted undisturbed soil surfaces do not begin to reach the same flux rate until much higher windspeeds, at which point crusts are broken and emissivity rates increase exponentially. Significantly, the particle emissivity of undisturbed, loose sandy soils mirrors that of disturbed surfaces in relation to windspeed and potential magnitude of dust emission. This finding suggests that the prevalent sandier, rangeland soils of the SHP could be equal or greater dust sources than cultivated fields during periods of sustained, severe aridity.